An IP address is an address in computer networks – such as the Internet – based on Internet Protocol (IP). It is assigned to devices that are connected to the network and makes the devices so addressed and so accessible. The IP address can designate a single recipient or a group of receivers (multicast, broadcast). Conversely, a computer has multiple IP addresses associated with it.
The IP address is used to transport data from its sender to the intended recipients. Similar to the mailing address on an envelope packets are provided with an IP address that uniquely identifies the recipient. Because of these can address the “post offices” to decide the routers, is to be transported in which direction the packet. Unlike IP addresses, postal addresses are not tied to a particular place.
The best known of today’s familiar notation IPv4 addresses consist of four numbers that lie between 0 and 255 and are separated by one point, for example, 192.168.1.1. Technically, the address of a 32-digit (IPv4) or 128-digit (IPv6) binary.
To establish a communication between two technical devices, each device must be able to send data to the other device. For these data to arrive at the correct remote, it must be clearly identified (addressed) are. This is done in IP networks with an IP address.
Thus, for example a web server from a web browser directly addressed by its IP address. The browser asks to for a domain name, to eg “www.example.com“, IP address with a name server and then speaks directly to the Web server in its IP-address “188.8.131.52″.
IP address in IP packets
Each IP packet starts with an information area for the transport through the IP-layer, the IP header. This header contains two fields, in which the IP addresses of both the sender and recipient to be entered before the data packet is sent. The mediation is done on layer 3 in the OSI model, the network layer.
Existing since the introduction of version 4 of Internet Protocols mainly used IPv4 addresses from 32 bits, so four octets (bytes). Thus 232, ie 4,294,967,296 addresses are displayed. In dotted decimal notation, the four octets are written as four dot-separated decimal integers in the range 0-255, for example: 192.168.1.1.
IPv6 – new version with a larger address space
Due to the rapidly growing demand for IP addresses is clearly seen that the usable address space of IPv4 will be exhausted sooner or later. Mainly for this reason, IPv6 was developed. It uses 128 bits to store addresses so are 2128 = 25 616 (= 340,282,366,920,938,463,463,374,607,431,768,211,456 ? 3.4 � 1038) addresses displayed. This number is sufficient to provide for every square millimeter of the surface at least 665.570.793.348.866.944 (= 6.65 � 1017) IP addresses.
Since the decimal would ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd confusing and unmanageable, to set IPv6 addresses in hexadecimal dar. To this representation To simplify further, two octets are combined and displayed in the address groups separated by a colon. XXXX: XXXX: XXXX: XXXX: XXXX: XXXX: XXXX: XXXX. Example: 2001:0 db8: 85a3: 08d3: 1319:8 a2e: 0370:7344